# Docker cool commands

## Tail logs

In the first steps of an app you can not configure graylog or complex log processing tools.
Search in docker logs is easy:

	docker logs -t --tail 1000 my_container

    docker logs -t --tail 1000 my_container 2>&1 | grep -i error

In previous example we are searching for error (case-insensitive) in the last 1000 log lines.

## Docker postgres/postgis backup

Docker backup command

	docker exec -it --env PGPASSWORD=[POSTGRESQL_PASSWORD] database_container pg_dump \
	 -h [POSTGRESQL_HOST] -p [POSTGRESQL_PORT] \
	 -U [POSTGRESQL_USER] [POSTGRESQL_DATABASE] | gzip -9 > backup.sql.gz

## Copy file from host to container

Simple file copy:

	docker cp script.js container_name:/app/

## Copy file from container

Simple file copy:

	docker cp container_name:/app/. .

## Cron task in docker-compose

Configuration for run cron tasks in docker. In this example, scripts in cron_tasks_folder will be executed hourly:

	version: '3'
    services:
      cron:
        image: alpine:3.6
        command: crond -f -l 8
        volumes:
         - ./cron_tasks_folder:/etc/periodic/hourly/:ro

## Remove all unused images

Be carefoul with this commands!!!
Command to remove all unused images:

	docker image prune -a

Command to remove dangling images:

	docker rmi $(docker images -q -f dangling=true)

Docker has a command to delete all stopped containers, dangling images, networks, unused volumes and build cache at the same time:

	docker system prune -a --volumes